Cylindrical Engine Bore

ABSTRACT

A cylinder bore including an inner surface including an axial travel area and an axial non-travel area including two discontinuous axial widths of the cylindrical bore and the axial travel area extending therebetween. A nominal diameter of the axial travel area is greater than that of the axial non-travel area. A plurality of annular grooves is formed in the two discontinuous axial widths of the cylindrical bore.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of Ser. No. 13/913,865, filed Jun. 10,2013, issued as U.S. Pat. No. ______ on ______. This application is alsorelated to the application having Ser. No. 13/461,160, filed May 1,2012, issued as U.S. Pat. No. 8,726,874 on May 20, 2014. Thisapplication is also related to the application having Ser. No.13/913,871, filed Jun. 10, 2013, the disclosures of which are herebyincorporated in their entirety by reference herein.

TECHNICAL FIELD

The present invention relates to cylindrical surfaces of cylindricalengine bores.

BACKGROUND

Automotive engine blocks include a number of cylindrical engine bores.The inner surface of each engine bore is machined so that the surface issuitable for use in automotive applications, e.g., exhibits suitablewear resistance and strength. The machining process may includeroughening the inner surface and subsequently applying a metalliccoating to the roughened surface and subsequently honing the metalliccoating to obtain a finished inner surface. Various surface rougheningtechniques are known in the art, but have suffered from one or moredrawbacks or disadvantages.

SUMMARY

In a first embodiment, a cylinder bore is disclosed. The cylinder boreincludes an inner surface including an axial travel area and an axialnon-travel area including two discontinuous axial widths of thecylindrical bore and the axial travel area extending therebetween. Anominal diameter of the axial travel area is greater than that of theaxial non-travel area. A plurality of annular grooves is formed in thetwo discontinuous axial widths of the cylindrical bore.

In a second embodiment, a cylinder bore is disclosed. The cylinder boreincludes first and second axial non-travel inner surface portions and anaxial travel inner surface portion extending therebetween. A nominaldiameter of the axial travel inner surface portion is greater than thatof the first and second axial non-travel inner surface portions. Aplurality of the annular grooves is formed in each of the first andsecond axial non-travel inner surface portions. A plurality of peaksextends between the plurality of annular grooves.

In a third embodiment, a cylinder bore is disclosed. The cylinder boreincludes first and second axial non-travel inner surface portions and anaxial travel inner surface portion extending therebetween. A nominaldiameter of the axial travel inner surface portion is greater than thatof the first and second axial non-travel inner surface portions. Aplurality of annular grooves is formed in each of the first and secondaxial non-travel areas and has a square wave shape of a uniformdimension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a top view of a joint or deck face of an exemplary engineblock of an internal combustion engine;

FIG. 2A depicts a pre-boring step in which an unprocessed cylinder boreinner surface is bored to a diameter;

FIG. 2B depicts an interpolating step in which a travel area is machinedusing a cutting tool to produce a recessed inner surface with a pocketand annular surface grooves;

FIG. 2C depicts a deforming step in which flat peaks between adjacentgrooves are deformed to obtain deformed peaks;

FIG. 2D depicts an interpolating step in which one or more of thenon-travel areas are machined using a cutting tool to form annulargrooves;

FIG. 2E shows a magnified, schematic view of annular grooves formed inthe non-travel areas of an engine bore;

FIG. 3A depicts a perspective view of a cutting tool according to oneembodiment;

FIG. 3B depicts a top view of cutting tool showing a top axial row ofcutting elements;

FIGS. 3C, 3D and 3E depict cross-sectional, schematic views of first andsecond groove cutting elements and pocket cutting elements taken alonglines 3C-3C, 3D-3D and 3E-3E of FIG. 3A, respectively;

FIG. 3F shows a cylindrical shank for mounting a cutting tool in a toolholder according to one embodiment;

FIG. 4A is a schematic, top view of a cylinder bore according to oneembodiment;

FIG. 4B is a schematic, side view of the cylinder bore of FIG. 4Baccording to one embodiment;

FIG. 5 shows an exploded, fragmented view of the inner surface of thecylinder bore before, during and after an interpolating step;

FIGS. 6A, 6B and 6C illustrate a swiper tool according to oneembodiment; and

FIG. 7 illustrates a magnified, cross-sectional view of the innersurface of a cylinder bore.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments known to theinventors. However, it should be understood that disclosed embodimentsare merely exemplary of the present invention which may be embodied invarious and alternative forms. Therefore, specific details disclosedherein are not to be interpreted as limiting, rather merely asrepresentative bases for teaching one skilled in the art to variouslyemploy the present invention.

Except where expressly indicated, all numerical quantities in thisdescription indicating amounts of material are to be understood asmodified by the word “about” in describing the broadest scope of thepresent invention.

Automotive engine blocks include a number of cylindrical engine bores.The inner surface of each engine bore is machined so that the surface issuitable for use in automotive applications, e.g., exhibits suitablewear resistance and strength. The machining process may includeroughening the inner surface and subsequently applying a metalliccoating to the roughened surface and subsequently honing the metalliccoating to obtain a finished inner surface with requisite strength andwear resistance. Alternatively, a liner material having requisitestrength and wear resistance characteristics may be applied to theunfinished inner surface of the engine bore.

Embodiments disclosed herein provide cutting tools and processes forroughening the inner surface of cylindrical bores, e.g., engine bores,to enhance the adhesion and bonding of a subsequently applied metalliccoating, e.g., thermal spray coating, onto the inner surface.Accordingly, the finished inner surface may have enhanced strength andwear resistance.

FIG. 1 depicts a top view of a joint face of an exemplary engine block100 of an internal combustion engine. The engine block includes cylinderbores 102, each of which includes an inner surface portion 104, whichmay be formed of a metal material, such as, but not limited to,aluminum, magnesium or iron, or an alloy thereof, or steel. In certainapplications, aluminum or magnesium alloy may be utilized because oftheir relatively light weight compared to steel or iron. The relativelylight weight aluminum or magnesium alloy materials may permit areduction in engine size and weight, which may improve engine poweroutput and fuel economy.

FIGS. 2A, 2B, 2C, 2D and 2E depict cross-sectional views of a cylinderbore inner surface relating to steps of a process for applying a profileto the inner surface of the cylinder bore. FIG. 2A depicts a pre-boringstep in which an unprocessed cylinder bore inner surface 200 is bored toa diameter that is less than the diameter of the finished, e.g., honed,diameter of the inner surface. In some variations, the difference indiameter is 150 to 250 microns (μms). In other variations, thedifference in diameter is 175 to 225 microns. In one variation, thedifference in diameter is 200 microns.

FIG. 2B depicts an interpolating step in which a travel area 202 ismachined into the pre-bored inner surface 200 using a cutting tool.Interpolation-based roughening can be accomplished with a cutting toolsuitable for cylinder bores of varying diameter. The cutting tool can beused to roughen only a selected area of the bore, such as the ringtravel area of the bore. Roughening only the ring travel portion of thebore may reduce coating cycle time, material consumption, honing timeand overspray of the crank case.

The length of the travel area corresponds to the distance in which apiston travels within the engine bore. In some variations, the length oftravel area 202 is 90 to 150 millimeters. In one variation, the lengthof travel area 202 is 117 millimeters. The travel area surface ismanufactured to resist wear caused by piston travel. The cutting toolforms annular grooves 204 (as shown in magnified area 208 of FIG. 2B)and a pocket 206 into the travel area 202. It should be understood thatthe number of grooves shown in magnified area 208 are simply exemplary.Dimension 210 shows the depth of pocket 206. Dimension 212 shows thedepth of annular grooves 204. In some variations, the groove depth is100 to 140 microns. In another variation, the groove depth is 120microns. In some variations, the pocket depth is 200 to 300 microns. Inanother variation, the pocket depth is 250 microns.

The pre-bored inner surface 200 also includes non-travel portions 214and 216. These areas are outside the axial travel distance of thepiston. Dimensions 218 and 220 show the length of non-travel portions214 and 216. In some variations, the length of non-travel area 214 is 2to 7 millimeters. In one variation, the length of non-travel area 214 is3.5 millimeters. In some variations, the length of non-travel area 216is 5 to 25 millimeters. In one variation, the length of non-travel area216 is 17 millimeters. The cutting tool and the interpolating step aredescribed in greater detail below.

FIG. 2C depicts a deforming step in which the flat peaks betweenadjacent grooves 204 are deformed to obtain deformed peaks 222 in whicheach peak 222 includes a pair of undercuts 224, as shown in magnifiedarea 226 of FIG. 2C. It should be understood that the number of deformedpeaks shown in magnified area 226 are simply exemplary. The deformingstep may be carried out using a swiping tool. The swiping tool and thedeforming step are described in greater detail below.

FIG. 2D depicts an interpolating step in which one or more of thenon-travel areas 214 and 216 are machined using a cutting tool to formannular grooves 228, as shown in magnified area 230 of FIG. 2E. Flatpeaks 232 extend between annular grooves 228. It should be understoodthat the number of grooves shown in magnified area 230 are simplyexemplary. In one embodiment, the grooves form a square wave shape of auniform dimension. In some variations, the dimension is 25 to 100microns. In one variation, the dimension is 50 microns. As described inmore detail below, the cutting tool may form a profile of grooves withinone or more of the non-travel areas 214 and 216.

FIG. 3A depicts a perspective view of a cutting tool 300 according toone embodiment. Cutting tool 300 includes a cylindrical body 302 andfirst, second, third and fourth axial rows 304, 306, 308 and 310 ofcutting elements. Cylindrical body 302 may be formed of steel orcemented tungsten carbide. The cutting elements may be formed of acutting tool material suitable for machining aluminum or magnesiumalloy. The considerations for selecting such materials include withoutlimitation chemical compatibility and/or hardness. Non-limiting examplesof such materials include, without limitation, high speed steel,sintered tungsten carbide or polycrystalline diamond. Each axial row304, 306, 308 and 310 includes 6 cutting elements. As shown in FIG. 3A,the 6 cutting elements are equally radially spaced apart from adjacentcutting elements. In other words, the six cutting elements are locatedat 0, 60, 120, 180, 240, and 300 degrees around the circumference of thecylindrical body 302. While 6 cutting elements are shown in FIG. 3A, anynumber of cutting elements may be used according to one or moreembodiments. In certain variations, 2 to 24 cutting elements areutilized.

FIG. 3B depicts a top view of cutting tool 300 showing the first axialrow 304 of cutting elements. As shown in FIG. 3B, the 0 degree cuttingelement includes a cutting surface 312 and a relief surface 314. Theother degree cutting elements include similar cutting and reliefsurfaces. The relief surface can otherwise be referred to as an endface. In the embodiment shown, each of the cutting elements is one ofthree types of cutting elements, i.e., a first type of groove cuttingelement (G1), a second type of groove cutting element (G2) and a pocketcutting element (P). In the embodiment shown in FIG. 3B, the 60 and 240degree cutting elements are the first type of groove cutting element;the 120 and 300 degree cutting elements are the second type of groovecutting element; and the 0 and 180 degree cutting elements are thepocket cutting element. Accordingly, the sequence of cutting elementsfrom 0 to 300 degrees is G1, G2, P, G1, G2 and P, as shown in FIG. 3B.However, it shall be understood that any sequence of cutting elements iswithin the scope of one or more embodiments. In some variations, thesequence is G1, P, G2, G1, P and G2 or P, G1, G1, P, G2 and G2. In theembodiment shown, two groove cutting elements are necessary due to thewidth and number of valleys between peaks, which exceed the number andwidths which can be cut with one element. For other groove geometries,one or three groove cutting elements may be used. The sequence ofcutting is not significant as long as all utilized elements are in theaxial row.

In the embodiment shown, the arrangement of teeth on the G1 and G2cutting elements are dimensioned differently. Regarding G1 shown in FIG.3C, tooth 332, which is closest to relief surface 322, has an outermostside wall that is flush with relief surface 322. Regarding G2 shown inFIG. 3D, tooth 350, which is closest to relief surface 340, has anoutermost side wall that is offset from relief surface 340. As shown inFIG. 3D, the offset is 400 microns. In other variations, the offset maybe 0 to 500 microns. Accordingly, there is a 400 micron offset betweenthe relief edge tooth of G1 and relief edge tooth of G2. The reliefsurface facing side of the sixth tooth 354 of G1 cutting element 318 andthe relief surface facing side of the fifth tool 356 of G2 cuttingelement 336 are offset from each other by 550 microns. These differingdimensions are utilized so that within each row of cutting elements, theG1 and G2 cutting elements can be axially offset from each other. Forexample, the axial offset may be 550 microns. In this embodiment, thisallows the edges to cut two separate rows of grooves, one by each offsetelement, with acceptable stress on the teeth.

In some variations, there is at least one of G1 and G2 and at least oneof P. As shown in FIG. 3A, the cutting elements in each row are offsetor staggered circumferentially from one another between each row, e.g.,each cutting element of the 0, 60, 120, 180, 240 and 300 degree cuttingelements is staggered by 60 degrees in adjacent rows. The staggeringimproves the lifetime of the cutting tool by smoothing out the initialcutting of the inner surface profile. If the cutting elements arealigned between adjacent rows, more force would be necessary to initiatethe cutting operation, and may cause more wear on the cutting elementsor deflection and vibration of the tool.

FIGS. 3C, 3D and 3E depict cross-sectional, schematic views of G1, G2and P cutting elements taken along lines 3C-3C, 3D-3D and 3E-3E of FIG.3B, respectively. Referring to FIG. 3C, a G1 cutting element 318 isshown having cutting surface 320, relief surface 322 and locatingsurface 324. The cutting surface 320 schematically includes a number ofteeth 326. It should be understood that the number of teeth shown aresimply exemplary. In certain variations, the number of teeth is 1 to 2per millimeter of axial length. In one variation, the number of teeth is1.25 teeth per axial length. Each tooth is rectangular in shape,although other shapes, e.g., square shapes, are contemplated by one ormore embodiments. Each tooth has a top surface 328 and side surfaces330. As shown in FIG. 3C, the length of top surface 328 is 250 micronsand the length of side surfaces 330 is 300 microns. In other variations,the length of the top surface is 200 to 400 microns and the length ofthe side surfaces is 200 to 500 microns. Flat valleys 358 extend betweenadjacent teeth 326. As shown in FIG. 3C, the width of the valley 358 is550 microns. In other variations, the width of the valley is 450 to1,000 microns. Cutting element 318 also includes a chamfer 334. In theembodiment shown, chamfer 334 is at a 15 degree angle. This chamferprovides stress relief and ease of mounting of the cutting elements. Inthe embodiment shown, the cutting elements are replaceable brazedpolycrystalline diamond elements. In other embodiments, replaceabletungsten carbide elements mounted in adjustable cartridges may be used.

Referring to FIG. 3D, a G2 cutting element 336 is shown having a cuttingsurface 338, a relief surface 340 and a locating surface 342. Thecutting surface 338 schematically includes a number of teeth 344. Itshould be understood that the number of teeth shown are simplyexemplary. In certain variations, the number of teeth is 1 to 2 teethper millimeter of axial length. In one variation, the number of teeth is1.25 per millimeter of axial length. Each tooth is rectangular in shape,although other shapes, e.g., square shapes, are contemplated by one ormore embodiments. Each tooth has a top surface 346 and side surfaces348. As shown in FIG. 3D, the length of top surface 346 is 250 micronsand the length of side surfaces 348 is 300 microns. In other variations,the length of the top surface is 200 to 400 microns and the length ofthe side surfaces is 200 to 500 microns. Tooth 350, which is closest torelief surface 340, has an outermost side wall that is offset fromrelief surface 340. As shown in FIG. 3D, the offset is 400 microns. Inother variations, the offset may be 0 to 500 microns. Flat valleys 358extend between adjacent teeth 344. As shown in FIG. 3D, the width of thevalley 360 is 550 microns. In other variations, the width of the valleyis 400 to 1,000 microns. Cutting element 336 also includes a chamfer352. In the embodiment shown, chamfer 352 is at a 15 degree angle. Thischamfer provides stress relief and ease of mounting of the cuttingelements. In the embodiment shown, the cutting elements are replaceablebrazed polycrystalline diamond elements. In other embodiments,replaceable tungsten carbide elements mounted in adjustable cartridgesmay be used.

In the embodiment shown, the arrangement of teeth on the G1 and G2cutting elements are dimensioned differently. Regarding G1 shown in FIG.3C, tooth 332, which is closest to relief surface 322, has an outermostside wall that is flush with relief surface 322. Regarding G2 shown inFIG. 3D, tooth 350, which is closest to relief surface 340, has anoutermost side wall that is offset from relief surface 340. As shown inFIG. 3D, the offset is 400 microns. In other variations, the offset maybe 0 to 500 microns. Accordingly, there is a 400 micron offset betweenthe relief edge tooth of G1 and relief edge tooth of G2. The reliefsurface facing side of the sixth tooth 354 of G1 cutting element 318 andthe relief surface facing side of the fifth tool 356 of G2 cuttingelement 336 are offset from each other by 550 microns. These differingdimensions are utilized so that within each row of cutting elements, theG1 and G2 cutting elements can be axially offset from each other. Forexample, the axial offset may be 550 microns. In this embodiment, thisallows the edges to cut two separate rows of grooves, one by each offsetelement, with acceptable stress on the teeth.

Referring to FIG. 3E, a P cutting element 362 is shown having a cuttingsurface 364, relief surface 366 and a locating surface 368. Cuttingsurface 364 is flat or generally flat, and has no teeth, in contrast tothe cutting surfaces of the G1 and G2 cutting elements, which are shownin phantom. The teeth shown in phantom line in FIG. 3E indicates thetooth geometry of the G1 and/or G2 cutting elements and how and thecutting surface 364 is radially offset away from the tooth top surfaces328 and 346. The P cutting element 362 removes a portion of the peaksbetween the grooves and creates the pocket. The amount of radial offsetcontrols the depth of the grooves cut in the bottom of the pocketdepicted in FIG. 2B. In the illustrated embodiment, the dimension 120microns in FIG. 3E is the depth of the grooves that are cut when the G1,G2 and P elements are used in combination. The dimension of 50.06millimeters is the diameter of the cutting tool measured to the topsurfaces (minimum diameter) of the teeth that are formed.

FIG. 3F shows a cylindrical shank 380 for mounting cutting tool 300 intoa tool holder for mounting in a machine spindle. In other embodiments,the shank may be replaced by a direct spindle connection, such as aCAT-V or HSK taper connection.

Having described the structure of cutting tool 300 according to oneembodiment, the following describes the use of cutting tool 300 tomachine a profile into an inner surface of a cylinder bore. FIG. 4A is aschematic, top view of a cylinder bore 400 according to one embodiment.FIG. 4B is a schematic, side view of cylinder bore 400 according to oneembodiment. As shown in FIG. 4A, cutting tool 300 is mounted in amachine tool spindle with an axis of rotation AT parallel to thecylinder bore axis AB. The tool axis AT is offset from the bore axis AB.The spindle may be either a box or motorized spindle. The tool rotatesin the spindle about its own axis AT at an angular speed Ω1 andprecesses around the bore axis AB at angular speed Ω2. This precessionis referred to as circular interpolation. The interpolating movementpermits the formation of a pocket and annular, parallel grooves withinthe inner surface of a cylinder bore.

In one embodiment, the aspect ratio of the diameter of the cutting toolDT to the inner diameter of the bore DB is considered. In certainvariations, the inner diameter is substantially greater than the cuttingtool diameter. In certain variations, the cutting tool diameter is 40 to60 millimeters. In certain variations, the inner diameter of thecylinder bore is 70 to 150 millimeters. Given this dimensionaldifference, this cutting tool may be utilized with a significantvariation in bore diameter. In other words, use of the cutting tools ofone or more embodiments does not require separate tooling for each borediameter.

Regarding the pre-boring step of FIG. 2A identified above, a boring bar(not shown) can be attached to a machine spindle to bore a diameter thatis less than the diameter of the finished diameter of the inner surface.In certain variations, the feed rate, i.e., the rate in which the boringbar is fed radially outward into the inner surface, of the spindle is0.1 to 0.3 mm/rev. In one or more embodiments, the spindle istelescoping. In other embodiments, the spindle may be fixed and the boremay move. In another variation, the feed rate is 0.2 mm/rev. In certainvariations, the rotational speed of the boring bar is 1,000 to 3,000rpms. In another variation, the rotational speed of the boring bar is2,000 rpms.

Regarding the interpolating step of FIG. 2B identified above, thecutting tool 300 is used to machine a profile into the inner surface ofcylinder bore 400. In certain variations, the interpolating feed rate(radially outward) of the spindle during this step is 0.1 to 0.3 mm/rev.In another variation, the feed rate is 0.2 mm/rev. In certainvariations, the rotational speed of cutting tool 300 is 3,000 to 10,000rpms. In another variation, the rotational speed of cutting tool 300 is6,000 rpms.

As described above, cutting tool 300 includes cylindrical body 302 thatincludes four rows of cutting elements. According to this embodiment,the axial length of the cut is 35 mm. Therefore, if the length of thetravel area is 105 mm, three axial steps are used to complete theinterpolating of the travel area. In other words, the axial position ofthe spindle is set at an upper, middle and lower position beforerotating the cutting tool at each of the positions. While 4 cuttingelement rows are shown in one embodiment, it is understood thatadditional rows may be utilized. For example, 6 rows may be used to cuta similar travel area in 2 axial steps instead of 3. Further, 12 rowsmay be used to cut a similar travel area in 1 axial step.

Moving to FIG. 4B, a fragmented portion of cylindrical body 302 ofcutting tool 300 and cutting elements from axial rows 304, 306, 308 and310 are schematically shown in overlapping relationship. As describedabove and shown in this FIG. 4B, there are overlaps 406, 408 and 410between adjacent cutting element rows. This overlap helps provideuniform and consistent profile cutting in boundary regions.

FIG. 5 shows an exploded, fragmented view of the inner surface 500 ofthe cylinder bore before, during and after the interpolating step. Thecutting tool 300 is fed radially outward into the surface of thecylinder bore at a rate of 0.2 mm per revolution. While the cutting tool300 is being fed into the inner surface, it is rotating at a speed of6,000 rpms. The P pocket cutting elements cut pocket 502 into the innersurface 500. The height of the pocket is H and the width is wv. The Hvalue corresponds to the axial offset between the valleys 358 of G1 andG2 cutting elements 318 and 336 and the cutting surface 364 of P cuttingelement 362. In a non-limiting, specific example, the offset is 250microns. Therefore, H is 250 microns. The wv value corresponds to thelength of the tooth upper surfaces 328 and 356 of the G1 and G2 cuttingelements 318 and 336. In the non-limiting, specific example set forthabove, the tooth upper surfaces have a length of 250 microns.Accordingly, wv is 250 microns.

The groove cutting elements G1 and G2 remove material 504 to createpeaks 506. The height of these peaks is h and the width is wp. In thenon-limiting, specific example shown, wp is 150 microns. The h value isdetermined by the radial offset between the top of groove cuttingelements G1 and G2 and the pocket cutting element P. In thenon-limiting, specific example set forth above, this offset is 120microns. Therefore, h is 120 microns. The wv value corresponds to thelength of the flat valleys between groove-cutting teeth top surfaces. Inthe non-limiting, specific example set forth above, the valley length is250 microns. Accordingly, wv is 250 microns. Given the rotational speedof cutting tool 300, the cutting of the pocket and annular groovesdescribed above occurs simultaneously or essentially simultaneously,e.g., for a period of time equal to a ⅙ revolution of the cutting tool300, if the cutting tool includes six cutting elements and adjacentelements are groove and pocket cutting elements.

Regarding the deforming step of FIG. 2C above, a swiper tool is used toswipe selective area flat peaks between grooves. As used herein incertain embodiments, “swipe” is one form of deforming the selectiveareas. In one embodiment, deforming does not include cutting or grindingthe selective area. These types of processes typically include completeor at least partial material removal. It should be understood that otherdeforming processes may be utilized in this step. Non-limiting examplesof other secondary processes include roller burnishing, diamond knurlingor a smearing process in which the flank of the pocket cutting tool isused as a wiper insert. In certain variations, the feed rate of thespindle during this step is 0.1 to 0.3 mm/rev. In another variation, thefeed rate is 0.2 mm/rev. In certain variations, the rotational speed ofswiper tool 300 is 5,000 to 7,000 rpms. In another variation, therotational speed of a swiper tool is 6,000 rpms.

FIGS. 6A, 6B and 6C illustrate a swiper tool 600 according to oneembodiment. FIG. 6A shows a top view of swiper tool 600. FIG. 6B shows amagnified view of region 602 of swiper tool 600. FIG. 6C shows a sideview of swiper tool 600, including cylindrical shank 604. Swiper tool600 includes 4 swiping projections 606, 608, 610 and 612. Each swipingprojection 606, 608, 610 and 612 project outward from the center 614 ofswiper tool 600. In one embodiment, the swiper tool has the samediameter as the cutting tool, and the swiper elements have the sameaxial length as the cutting elements, so that the swiping tool and thecutting tool may be run over the same tool path to simplify programmingand reduce motion errors. Each swiping projection includes reliefsurface 616, a back surface 618, and a rake surface 620. A chamfer 622extends between rake surface 620 and relief surface 616. The chamfer orlike edge preparation, such as a hone, is used to ensure that the tooldeforms the peaks instead of cutting them. In one variation, the angleof the chamfer 622 relative to the landing surface 616 is 15 degrees. Inother variations, the angle is 10 to 20 degrees, or a hone with a radiusof 25 to 100 microns. In one embodiment, the angle between the rakesurface and the relief surface of adjacent swiping projections is 110degrees.

The swiping tool 602 is dull enough that it does not cut into the innersurface of the cylinder bore. Instead, the swiping tool 602 mechanicallydeforms grooves formed in the inner surface of the cylinder bore. Movingback to FIG. 5, the swiping tool 600, used according to the methodsidentified above, created undercuts 508 and elongates upper surface 510.As shown in FIG. 5, the difference between h (the height of thenon-deformed peak) and the height of the deformed peak is Δh. In onevariation, Δh is 10 microns, while in other variations, Δh may be 5 to60 microns. The undercuts increase the adhesion of a subsequent thermalspray coating onto the roughened inner surface of the cylinder bore.

The machined surface after the pocket grooving step and the swiping stephas one or more advantages over other roughening processes. First,adhesion strength of the metal spray may be improved by using theswiping step instead of other secondary processes, such as diamondknurling, roller burnishing. The adhesion strength was tested using apull test. The adhesion strength may be in the range of 40 to 70 MPa. Inother variations, the adhesion strength may be 50 to 60 MPa. Compared tothe adhesion strength of a diamond knurling process, the adhesionstrength of swiping is at least 20% higher. Further, the Applicants haverecognized that adhesion is independent of profile depth of the groovesafter the first processing step. This may be advantageous for at leasttwo reasons. The swiping tool cuts relatively lower profile depthscompared to conventional processes, such as diamond knurling, rollerburnishing. In certain variations, the reduction in profile depth is 30to 40%. Accordingly, less metal spray material is necessary to fill theprofile while not compromising adhesion strength. Also, any variation inthe depth of the grooves does not affect the adhesion strength, whichmakes the swiping step more robust than conventional processes. Asanother benefit of one or more embodiments, the swiping tool can beoperated at much higher operational speeds than other processes, such asroller burnishing.

Regarding the interpolating step of FIG. 2D above, the cutting tool 300is used to machine non-travel areas 214 and 216 to form annular grooves.In certain variations, the feed rate of the spindle during this step is0.1 to 0.3 mm/rev. In another variation, the feed rate is 0.2 mm/rev. Incertain variations, the rotational speed of cutting tool 300 is 3,000 to10,000 rpms. In another variation, the rotational speed of a cuttingtool is 6,000 rpms.

These non-travel areas do not require a subsequent metal spray. However,a torch for metal spraying typically stays on throughout the sprayprocess. If these non-ring travel areas are not roughened, then spraymetal that is inadvertently sprayed on these areas do not adhere,causing delamination. This delamination may fall into the bore duringhoning and become entrapped between the honing stones and bore walls,causing unacceptable scratching. The delamination may also fall into thecrank case, which would then require removal. As such, by applying theannual grooves identified herein to the non-ring travel areas, thermalspray material adheres during the spray process and mitigatescontamination of the intended spray surface and the crank case. Thelightly sprayed non-ring travel areas may be easily removed duringsubsequent honing operation.

FIG. 7 illustrates a magnified, cross-sectional view of the innersurface of cylinder bore 200. Non-travel surface 214 includes annular,square grooves 230. Travel surface 202 includes annular grooves 206 andpocket 208.

While the best mode for carrying out the invention has been described indetail, those familiar with the art to which this invention relates willrecognize various alternative designs and embodiments for practicing theinvention as defined by the following claims.

What is claimed is:
 1. A cylinder bore comprising: an inner surfaceincluding an axial travel area and an axial non-travel area includingtwo discontinuous axial widths of the cylindrical bore and the axialtravel area extending therebetween, a nominal diameter of the axialtravel area is greater than that of the axial non-travel area; and aplurality of annular grooves formed in the two discontinuous axialwidths of the cylindrical bore.
 2. The cylinder bore of claim 1, whereinan aspect ratio of a depth of the plurality of annular grooves to awidth of the plurality of annular grooves is 0.5 or less.
 3. Thecylinder bore of claim 1, further comprising upper and lower circularedges.
 4. The cylinder bore of claim 1, wherein each of the twodiscontinuous axial widths of the axial non-travel area is 5 to 25millimeters.
 5. The cylinder bore of claim 1, wherein each of the twodiscontinuous axial widths of the axial non-travel area is 2 to 7millimeters.
 6. The cylinder bore of claim 1, wherein the axial travelarea includes a plurality of grooves.
 7. The cylinder bore of claim 6,wherein the plurality of grooves of the axial travel area has a squarewave shape of a uniform dimension,
 8. A cylinder bore comprising: firstand second axial non-travel inner surface portions and an axial travelinner surface portion extending therebetween, a nominal diameter of theaxial travel inner surface portion is greater than that of the first andsecond axial non-travel inner surface portions; a plurality of annulargrooves formed in each of the first and second axial non-travel innersurface portions; and a plurality of peaks extending between theplurality of annular grooves.
 9. The cylinder bore of claim 8, whereinthe plurality of peaks is a plurality of flat peaks.
 10. The cylinderbore of claim 8, wherein an aspect ratio of a depth of the plurality ofannular grooves to a width of the plurality of annular grooves is 0.5 orless.
 11. The cylinder bore of claim 8, further comprising upper andlower circular edges.
 12. The cylinder bore of claim 8, wherein each ofthe first and second axial non-travel inner surface portions has a widthof 5 to 25 millimeters.
 13. The cylinder bore of claim 8, wherein eachof the first and second axial non-travel inner surface portions has awidth of 5 to 25 millimeters.
 14. The cylinder bore of claim 8, whereinthe axial travel inner surface portions includes a plurality of grooves.15. A cylinder bore comprising: first and second axial non-travel innersurface portions and an axial travel inner surface portion extendingtherebetween, a nominal diameter of the axial travel inner surfaceportion is greater than that of the first and second axial non-travelinner surface portions; and a plurality of annular grooves formed ineach of the first and second axial non-travel areas of a square waveshape of a uniform dimension.
 16. The cylinder bore of claim 15, whereinthe uniform dimension is 25 to 100 microns.
 17. The cylinder bore ofclaim 15, wherein the uniform dimension is 50 microns.
 18. The cylinderbore of claim 15, wherein an aspect ratio of a depth of the plurality ofannular grooves to a width of the plurality of annular grooves is 0.5 orless.
 19. The cylinder bore of claim 15, further comprising upper andlower circular edges.
 20. The cylinder bore of claim 15, wherein each ofthe first and second axial non-travel inner surface portions has a widthof 5 to 25 millimeters.